Tool-operating attachment



June 28, 1949.- H. R. BILLETER 2,474,720

TOOL-OPERATING ATTACHMENT Filed Jan. 17, 1946 2 Sheets-Sheet 1 3.1 i Ti596 IN V EN TOR.

Patented June 28, 1949 UNITED STATES i TENT OFFICE 2 Claims.

This invention relates to an improved tooloperating attachment formachine tools, more particularly to an improved device for attachment todrill presses to operate twist drills in such manner as to regularlrepeatedly interrupt the cut or cuts being made by the drill and so thatmaterial is removed from the Work in the form of short chips whichreadily clear from the drill and work instead of in the form of longcurled chips which not orly may not readily clear from the drill andwork but also interfere with the supply of coolant and cause some dangerto the machine operator.

An object of the present invention is to provide an improved device ofthe character indicated above which is simple in construction,inexpensive of manufacture and has high durability.

A further object is to provide a twist drill operating attachment fordrill presses and the like which will provide an improved cutting andchip-breaking action of the drill.

A further object of the invention is to provide a twist drill operatingattachment for drill presses and the like which will regularlyrepeatedlyinterrupt the cut or cuts made by the drill in such relationto the rotation of the drill that the points of successive withdrawalsand re-entries of the cutting edge or edges of the drill from and intothe material of the work piece regularly progress around the axis of thedril1hole so as to elimi nate the tendency of the drill to produce askewed hole which frequently occurs when such successive points ofwithdrawal and re-entr of the cutting edges fall in a line or linesparallel to the axis of the drill-hole.

Two preferred structural embodiments of the invention are illustrated byway of example in the accompanying drawings in which:

Figure l is a vertical and longitudinal section along the axis of oneform of construction embodying the invention;

Fig. 2 is an elevation of the lower ball bearing race which is carriedby and rotates with the tool supporting spindle of the device of Fig. 1;

Fig. 3 is a top plan of the race of Fig. 2 show ing the proportions andarrangement of the cam falls, rises and dwells thereof;

Fig. 4 is a schematic diagram illustrating the planetary gearcharacteristics of the bearing balls and races of the device of Fig. 1;

Fig. 5 is a schematic illustration of the cuttin action of aconventional two-fluted spiral twist drill operated b the device of Fig.1;

Fig. 6 is a section similar to Fig. l but of a modified form ofconstruction also embodying the invention;

Fig. 7 is an elevation of the lower ball bearing race which is carriedby and rotates with the tool carrying spindle of the modified device ofFig. 6;

Fig. 8 is a top plan of the race member of Fig. 7 showing theproportions and arrangement of the cam falls, rises and dwells thereof;

Fig. 9 is a diagram schematically illustrating the planetary gear actionof the balls and races of the lower ball bearing of the device of Fig.6; and

Fig. 10 is a schematic illustration of the cutting action of aconventional two-fluted spiral twist drill operated through the deviceof Fig. 6.

In the device of Fig. l the drive shank 2!, which has a taper to fit thespindle of the drill press or other machine tool with which the deviceof the present invention is to be employed or is otherwise adapted forattachment to such spindle, is formed at its lower end with aninternally threaded axially centered socket 22 into which is screwed theupper threaded end of a sleeve 23 having a centered axial bore which, inturn, receives the upper end portion of the tool spindle 24. A pin 25passes through the sleeve 23 and spindle 24 and has a reducedcylindrical end portion 26 to fit a small radial bore in one side of thesleeve 23, a larger cylindrical head portion to fit the radial bore oflarger diameter in the opposite side of the sleeve 23, and flattenedside portions 27 intermediate its large and small cylindrical ends tofit closely the sides of vertically elongated radial slots in oppositesides of the spindle 24. A compression spring 2% contained in an axialbore in the upper end ofthe tool spindle 24 seats at its lower endagainst the pin 25 and is compressed b a plug 29 threaded into the upperend of the bore in the spindle 24, so that the spring 28 yieldinglyurges the spindle 24 upwardly relative to the sleeve 23 and shank 2|.

The lower end of the sleeve 23 is formed as one race 3d of a ballbearing comprising also the balls 3|, a lower race member 32 and anouter race member 33 and a ball-spacing cage 3 1. The generallycylindrical lower race member 32, having a ball-race surface formed onits upper end, has an upwardly narrowing tapered or conical bore to fita tapered portion of the spindle 24 whereby the lower race member 32 maybe secured on the spindle 24 for rotation therewith. The outer racemember 33 is formed with alower cylindrical bore providing the outerrace for the balls 3! and is adapted to receive, in its lower end, aclosure ring 35 which has a flange to seat against the lower end of themember 33 and is suitably secured in place as by means of a set screw36. The lower race and the ring 35 are formed with a running fit betweenthem so as to close the lower end of the member 33 against the entranceor" chips and dirt. The upper end of the stationary race member 33 hasan axial cylinder bore of reduced diameter with an annular shoulder 31between it and the lower larger bore in member 33. The shoulder 3'!bears against an annular flange 38 formed on the sleeve 23 whereby thestationary racernember tl is held against vertical displacement betweenthe annular flange 38 and the lower eridof theshank 2|. Ihe race member33 has a ru nning fit with the flange 33, sleeve 23 and shank 2|.

The stationary racemember 33 has an-eutrigger rod 39 threaded radiallyonto it, said rod being" adapted to engage against the drill presscolumn or other stationary member of or on-the machine" towhicntheidevice is attached. v

"-It'will be apparentthatas the shank 2| is driven during operation ofthe drillpress or other machine, the sleeve 23 will rotate with theshank"and,through the pin 25, will also drive the spindle 24. 'Thesp'in'dle24; s1eeve--23and shank 2| thus rotate as" a' unit'but because of thevertical elon- 'gation'o-f theiradialslots inthe spindle 24' throughwhich" the pin 25*passes the -spindle '24 '-may move verticallya'shortdistancetrelative to the sleeve 23 and shank 2|. The spring 28 keeps therace 32 "pressedtightly againstithe balls 3 I" and keeps the "ballspressed 'tightlyagainst'the race '30 and race 33. It will be apparentthat*as-the races3ll and 32 rotate in' unison", the ballswillbe rotatedon "vertical axesas' they'roll'ontheir equators on the stationary"race33"and on'zjtheir 60"north and south parallels 'on' the races 30 and 32,respe'ctively. 0bvious1y,"the" balls 3| will progress in their orbitsaroundthe'interior of-the-stationary race 33 at a 'rateslower'th'an therotation of the races 39 and 32rotating'-with thespindle 24.

' Inthe device 'of Fig.1 there arethreeballs 3| "spaced 120 apartint-three openings'in the spacing "member '3 a; and" the race surface ofthe race member "32 *has formed in it three e'q'ually' Spacedcamdepressions All; the proportions-and arrangement of whichare'illustrat'ed in Fig. '3 from which it will 'fformed so thatthecurvature'in the section is of a 'g'leaterr'a'dii than thera'dii 0fthe'balls 3 I ,SO that the balls have substantially point contacts-withthe races 30 and32'fso that 'thetrackof the balls upon ther'ace's andviceve'rsa willbe substantially lines rather "than'areasu The-contactbr'pit'ch line of the'ball's'on the lower race-"departs only slightly froma" completec'ircular form and only by reason of thedepressi'ons'"4n-rormedfinthe race surface.

It 'will'be apparent that therate of progression of the halls 3| aroundtheir orbit'relativeto the rate'of rotationof the spindle! will bedetermined by 'thepitcl'i diameters of the'various contact ''-or tracklines on" thebea'ring parts in" accordance with the principles of aplanetary gear. The planetary gear effect of the ball bearing of thedevice of Fig. 1 is illustrated schematically in Fig. 4 in which a isthe diameter of the tracks of the balls 3| upon the race members 3|] and32; b is the diameter of the track of the race 32 upon a ball 3|; 0 isthe diameter of the track of the stationary outer race 33 upon the sameball 3|; and d is the diameter of the track of the balls 3| upon thestationaryouter race 33.-

-Thus it will be ap- '-p'arentthat; as the lower race 32r'otate'sclockwise with the shank 2| and spindle 24 during the operationof the device, the balls 3| will progress clockwise in-their orbit at arate less than the rate of tat'ion o'f'the race 32. Starting with theballs rotation of the spindle 24 and races 32 and 32 will"cause"theballsto roll up out of the cam depress'ions, thus forcing therace 32, spindle 24 and the drill downward. Each time the spindle 24rotates 12Q farther than the balls 3| progress in their orbit, each oithe three balls will again be centered the next-following camdepressio-nsdll in theracef32. As the balls roll into-the camdepressions 4 9, the-spring28, keeping the race -32 pressedtightlyagairist the balls 3| will raise the spindlefflandflwillliitfthe'cuttipgedge or edges of the drill clear of the bottomof the drill hole, thus interrupting the cut and breakingthe chip orchips. As the rotation of; the drive shank 2|, spindle 24 and drillcontinu es-,and the balls again roll up the rising si'des o'f thedepressions 4 0; the race 32, "spindle" 24 and drillare' Iagain" forceddownwardly to start a new which willcontinue until the spindle and"rae32"have rotatedfar enou'glrtoca'use the balls to roll into the nextfollowing depre'ssions dfl. This will happenrepatedly' each' timefthespincue 24" and race 32' have rotated another 120 ahead of the balls 3|.

The lengths "of the cutsand frequency of "the breaks in thechipfesulting from a form of construction such as shown" is Fig. {maybede'termined as follows:

Let

a=thelpitch di'aineterof the races? rotating with l t s nbtliediameteridr the track o'f the" rbtatmg spin- I dle racer-320i; theball "3 I; v c=thef diameter *offthe track'-' of' the stationary race'33 "on theballtl; d=the pitchd meter-of theistationary rac 33; e=thenumb r'ecuallyspaced' cam depressions 40'aswella's any wholenumber of'times the number of rolling bearii'ig elem*ehts 3! 'n'='a'ny"whblei'iuinber r="one" r evollitior'i' orfi 60 w -rotation"offthefspihdle; y'="the advance of the parser their-orbit i andz=rotation of-th 'spindle"rac '32' in advance ot the balls 31.

'Then:

ra 2 (b'y definition) and starnne withfth' ba'lls 'centered in the-"camdepressions 'dn infthe -'race'32;*the -pa11s wiltaga'in be centered inthe" am -"depressibn's each time the rotating spindle"24 ahd the' race32 having the the depressions 40 therein.

depressions 40 formed therein rotate ahead of the balls to the extent ofi. e., whenever and so that the balls would be centered in the camdepressions 40 each time a, the rotation of the spindle 24 and race 32in advance of the balls,

became equal to or of a revolution.

The foregoing calculations or estimates leave out of consideration thevery slight lengthening of the circumference of the pitch circle of therace 32 caused by the depressions 40. i

Fig. 5 illustrates schematically the cutting action of a standardtwo-fluted twist drill operated with the specific device just described.Starting with theballs 3| centered in the cam depressions 4|], the first7 26 or 41% of a revolution of the drive shank 2|, spindle 24 and drillwill roll the balls out of the cam depressions 40 to the beginning ofthe 80 dwells on the race 32. Assume that the consequent lowering of thedrill causes the cutting edges thereof to enter the work material andstart cutting. The cuts will progress normally with the normal feedduring the next of 249 or 166% of the rotation of the shank 2| andspindle 24 at which time the balls will be at the ends of the dwellportions of the cam race 32 and. will enter the falling sides of Duringthe next 41 3 of the rotation of. the drill, the balls 3| will roll downthe falling inclines of the depressions 4t permitting the spring 28 tolift the drill a. distance corresponding to the depth of the depressions40 less, however, the amount of normal feed which occurs during thatportion of ,the rotation of the spindle 24. Assuming a normal feed lessthan the depth of the depressions 4|], and in view of the fact that thedrill has two cutting edges, the cutting edges will be gradually -jsions40 forcing the cutting edges of the drill 6 back into the work prior tothe time the rotation of the drill reaches the 263 point, after whichthe balls will roll on the 80 dwells and the cam race 32 and the drillwill be advanced into the work by the normal feed and make another outduring the next 166% of rotation of the drill.

It will be seen that with the parts dimensioned as in the example given,the periodic alignments of the balls with the centers of the depressions'40 will occur, at each 249 7 of rotation of the drive shank 2|, spindle24 and the drill. In other words, starting with the balls in the centersof the depressions 40 the balls will again be centered in thedepressions when the drill has rotated to 249% to one revolution plus138 to two revolutions plus 27% to two revolutions plus 276 7 to threerevolutions plus 166% to four revolutions plus 55%;", to fourrevolutions plus 304% and so on.

These figures have been determined as though the work material offeredno resistance to the cutting edges and did not react on the drill andthe device driving it, and without taking into consideration any of themany variable factors such as the yielding of the various elements understress during the cutting action. However, the figures so obtained willserve to show the nature of the cut-interrupting and chip-breakingaction which is produced.

It will be apparent that the cutting edges are retracted as theballs 3|roll on the falling sides of the cam depressions 4E! and, provided thatthe normal feed for a two-fluted spiral twist drill is less than twicethe maximum depth of the cam depressions 40 where they intersect thepitch circle of the race 32, the cutting edges will be drawn out of theout and the chip will be broken prior to the time the balls reach thecenters of the depressions 40. Then as the balls roll up the risingsides of the cam depressions, the cutting edges of the drill are forcedback into the work and commence the cutting of any chips prior to thetime that the balls reach the top of the rises of the cam depressions.

The cutting action for a two-fluted spiral twist drill operated by adevice according to Fig. 1 with the specific dimensions given above byway of example is illustrated schematically in Fig. 5 which is drawn asthough the rotation of the drill started with the balls 3| centered inthe depressions ill, and also on an assumption that the automatic feedis approximately equal to the depth of the depressions 4-0 so that thetwo cut"- ting edges of the drill are brought into contact with the workwhen the balls 3| have rolled half way up the rising sides of thedepressions 40. Fig. 5 also entirely omits consideration of all variablefactors, such as compression, torsion and other deformations of thevarious parts of the device,

the tool operated thereby and the material of the work.

It will be seen that the successive withdrawals and re-entries of thecutting edges from and into the work occur at points which advanceprogressively around the axis of the hole being drilled in the workwhich prevents the repeated withdrawals and re-entries of the cuttingedges from and into the material of the work from causing the hole beingdrilled to depart from the axis of the spindle of the machine as wouldbe likely to occur if the beginnings and ends, respectively, ofsuccessive cuts were aligned parallel to the axis of the drill holeinstead of in relatively flat spirals around the axis of the drillhole.-

It will be apparent that if the parts were so ianmgteo thatthis sameeifect would be produced if the =n=umber oi revolutions of the spindle'which produced successivecenteri-ngs of the-balls 3 I inthe depressions40* were-equal to "any-multiple of the reciprocal of the number ofcutting edges ofithe drill. H0wever ,'by-sodimensioning 'theyparts astoproduce the illustrated; progression "offthe points ofsuccessive-exits and re-entries-of'the cutting edgesfrom and into thework material, such=tendencies are eliminated.

---Fig."6 showsaisecondiform 30f construction embodying-the"'inventionwherein" the "drive Fshank M may be-the same asthedrive'shank 2| oi -Fig. I. The sleeve'43 ofFigf 6 is also likel'thesleeve 23 of Fig. 1 exceptthatit's lower;end issnot formed as'ara'ce'fortheballs '5I. Whereas, in the device of Fig. 1, the 'feedpressureis transmitted -fromshank 2| 'through the sleeve 23 and'thence"through the balls 3I'"to the racel32; and spindle 24 in the device ofFig." v6 "the; feed pressureiis transmitted iromtheidrive shank 4| toaljcolla'r "51, 'and'then through the bearing .balls L58v to thestationaryrace member53 which .is formed'with the race 50 through whichthe feed pressure is transmitted. through the balls 5| to. the race.member 52 on'the spindle. A. sleeve 59 surrounds the adjacent ends ofthe.co1lar1.51. and stationary race member53 to excludedirtfrom.-the-balls 58 andthe races on whichthey rotate-theballs being. heldproperly spaced. bnisuitablemspacing member 69.

In the device .of Fig-Gthere .are.--.two.ba11s 5| which are. held 180%.apart. bythespacing; cage .54 .and the race member '52 isaccordingly,formed with two cam depressions 60; centered--180."..-.apart in therace, formed on the upper: end of the member 52; Thepoi-nts .of contactof theraces 5ll.and 520m the balls. 5] are displaced 30.from: thevertical. onoppositesides soathatItheflballs rotate ion-axes displaced30f. from the horizontal. and 'both races trackon the .equators, of theballs.

. .It will be readilyapparent. thatthe device. of Fig.6 operates onthesameprinciple. as the-device of Fig. 1 as. already..described...While.-.-the .planetarygearing principle-of thepballstfil; and races55] and 52 of the device of Fig. 6 is slightly .difierent'from thearrangementinthe; device of Fig; 1- because, as illustrated in Fig-. 9,,moth-races 50 and 52trackon the equators' of the-balls 5|, the: method:of calculatingthe action of thedeivice :oi -Fig. I is :also'applicable: to the device -1-of "Fig. 6 it being only necessary-togive-\both of "the elements b and c the "value of the :diameter 'of theballs 5|. Accordingly; it will be foun'd-that starting withth'e-balls5'lcentered-in the depressions 60, they willmagain be centeredinthedepressions 69 upon-each 294 /11 or-' /1'1 :oi" a'-'-rotationof' thedrive sh'ank- 4| and drill. The action imparted to the cutting edges-ofa-two=fiuted twist drill; will as illustrated in FigrlO be essentiallysimilar to the actio'n"illustratect in Riga-5am have the sameadvantages.

As shown in Figs. 3 and 8, the formation of the depressions 40 and 60 inthe race portions of the members 32 and 52 is such that the deprfissionsoccupy of the pitch circumference of the race, whereas the dwells occupythe remaining of the pitch circumference. In the two devicesi1-lustratecl, the rises, and falls of the cam depressions are equal andsymmetrical so that the rises and falls each individually occupy 20 ofthe pitchacircumference of thesraceztz butBOR. ot the pitch.circumference otthe racei352. .wHowevler, the depressions: may :be.ofisa'nyf.desiredvformwx- -cept that the rises: and :fallst should notbe. iniciined sousteeplyzrthat the a tangent iof Ethel angle-iof-inclination at any point exceeds thecoefiioient ofifrictionibetween the ballssandflthe. race..;in 'whichlthe:camdepressionsflfl or 6B are-formed. -"I:he"depth:of.the cam depressions Atend-'69 at their centers should be a little greater than zt-he productof themaximumanticipated feed per revolution andthenumber-of cuts whichthe tool makes per revolution (two in the case of a double fluted spiraltwist drill).

It will be readily apparent that in the device of Fig. 6 the camdepressions may be formed in either- 'of the two-races 50v or" 52. i "Inthe device of Fig. l, the cam depressions could be formed *in-any one ofthethree-races-3fl;-33,;or 32,-though the action is somewhat betterwhen-the depressions Ml are formed eitherin the race 32 or in the race3! rather than in-the race 33. In the latter case it Would be apparentthat the balls would repeatedly Joe squeezed: out .from between theraces 3i! and 32 and again forced between those two races tospread:{themeapartasgithe balls 3! -ro1ler;int0 andout .of depressionstermed win; the-:stationary race .33; .llhis wo,uld;-.cause.arsii'dinguofvtheballs ,upon rthev -racess'lsll; and 232 which would:tend "to produce some-wear. :However-,2 it will: "be seen ithat; asuchxwearz:wquldi'in t ioccun "at any looalizedipoints on 2 either raceibe-:causethe rate of, progression:of: :the-:;.ba1lsra 111;nd therraces;isisuch that;thecsuccessive ;:entries: .-:of the :balls; 5.1; into the;cam depressions; occ,urs =at progressively idisplaced. points;;.-around rthfiz. circumference: of; the:. -ra'c.es. i :It will also beseennthatrzinnplacerof thepr b'all hear-ingest, 131 32,133 or -50, 51.52; bearings havingiotherformsv ofrrolling; elements-may beemployed.The number of balls ,or-otherrolling elezments 0f the bearingisupreferablyl equal to. the numberof cam depressions 40.orififibutqtheinumibBI'A oitsuchwcamiv depressionssmay Joe. iany:iwhole :multiple of. the number Of/103,118..01 0thv91r1011i113:elements the latter number. being suitedrtorthe -:desired'- frequencyof. interruptionsofsthei out or cuts .-.made :by. the tool.

H'Itiis also apparentithat the inventions-instead iofi-beingrconstructedin: the form of. an 'attacln rment for a -machine tool-,amay bebuiltfidirectly into thezmachinetoolitself. So, -for example,iwheniincorporating i the invention in an otherwise conventionaldrillpress; the drive -shank, designated 2 hand 4 I'--i1ithe herein:disclosedat- =tachments may be omitted; the lower-end portion ofthedril-l press spindle maybe formed to serve the functionsof the 1sleeve 23 ch -wand the drill press' quill may" be for-med to-serve asthe non-rotatablerace 33 orf'53; or a stationary =race like-the=race 33'or 53 may; Joe formedas a.

"separate member secured-tothe quill. Alterna- 9 spindle and quill maybe replaced by a bearing like the bearing 50, 5|, 52, 60 of Fig. 4 or bya bearing functioning in the manner of the bearing 30, 3|, 32, 33 ofFig. 1 or 50, 5|, 52, 6!) of Fig. 4.

From the foregoing, it will be apparent that the invention may beembodied in structures varying in various respects from the structuresillustrated in the accompanying drawings and that by variouslydimensioning the balls, races and cam depressions substantially anydesired type of action of the tool operated by the device may besecured. Also, in place of the illustrated conventional three jaw chucksillustrated, the attachment may be provided with other forms of toolholding means. Various other modifications of structural form and detailmay be made within the scope of the invention.

From the above descriptions of the structure and mode of operation, itwill be apparent that the progression of the chip-breaking action of thedrill around the periphery of the hole being drilled results from thestructural arrangement wherein the rolling element is caused to movearound the fixed race an angular amount different from its angularmovement relative to the rotating race during any given period ofoperation. The fact that those relative angular movements are unequalresults in the rolling element meeting the depression in the one race attimes when the rolling element has moved an angular distance about thefixed race that is not a simple factor of the angular movement relativeto the rotating race. In the specific embodiment shown, that differencein angular movement results primarily from the fact that the rollingelement contacts the races at respectively dilferent distances from theaxis of the spindle. Other modifications will be readily apparent tothose skilled in the art after studying the disclosures herein.

I claim:

1. In a chip breaking drill operating means having a rotatable spindle,a rotatable bearing race on said spindle and a non-rotating racearranged about said spindle, a rolling bearing element between saidraces in rolling contact therewith and a surface irregularity in one ofsaid faces to be engaged by said element to retract a drill from a workpiece; the improvement comprising, said races and element being soconstructed and arranged that said element engages said races atrespectively different efiective distances from the axis of said spindlewhereby successive engagements of said element with said surfaceirregularity occur at angularly displaced positions about the axis ofsaid spindle.

2. In a chip breaking drill operating means having a rotatable spindle,a rotatable bearing race on said spindle and a non-rotating racearranged about said spindle, a rolling bearing element between saidraces in rolling contact therewith and a surface irregularity in one ofsaid races to be engaged by said element to retract a drill from a workpiece, the improvement wherein the diameters of the circles of contactbetween said element and races are so related that rotation of saidelement on its axis of rotation will cause said element to have anangular movement about said non-rotating race different from its angularmovement relative to said rotatable race whereby successive engagementsof said element with said surface irregularity occur at angularlydisplaced positions about the axis of said spindle.

HENRY ROBERT BILLETER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,196,656 Bugbee Aug. 29, 19161,523,629 Bulloch Jan. 20, 1925 2,391,463 Kingsbury Dec. 25, 19452,430,019 Jenkins Nov. 4, 1947 Certificate of Correction Patent No.2,474,720 June 28, 1949 HENRY ROBERT BILLETER It is hereby certifiedthat errors appear in the printed specification of the above numberedpatent requiring correction as follows:

Column 3, line 10, for the Word cylinder read cylindrical; column 4,li'ri'es 66 and 67, for 1 a c w a 0 ea Miss 67 column 5, line 35, for2493/13 read 2498/13; column 8, line 38, for roller read rolled; column10, line 5, for faces read races;

and that the said Letters Patent should be read with these correctionstherein that the same may conform to the record of the case in thePatent Ofiice.

Signed and sealed 20th day of December; A. D. 1949.

THOMAS F. MURPHY,

Assistant Uommim'oner of Patents.

